The Structure and Function of the Frontal Lobe
In collaboration with C. Bernard, A. Smith, & D. Whiteside
The frontal lobe has been referred to as the emotional control center and the residing place of human personality (Levin et al., 1987). Its location at the front of the head creates a definitive vulnerability and studies have shown that it is the most common area of brain injury (Levin et al., 1987). Damage to this area can cause a wide variety of incapacitating symptoms as it plays a significant role in movement, critical thinking and problem solving, memory, language, judgment, impulse control, and the complex and uniquely human accountability to appropriate social behavior (Wickens, 2005). Perhaps the most severe loss from damage to the frontal lobes is the personally defining personality characteristics that account for the exclusively human quality of higher cognitive functions that seem to accompany social interaction (Bird, Castelli, Malik, Frith, & Husain, 2004).
A Brief Description of the Frontal Lobe
The frontal lobe is at the front of the cerebral hemispheres, in front of the parietal lobes, and above the temporal lobes, and behind the forehead (Wickens, 2005). There are two frontal lobes, one on the left and one on the right (Wickens, 2005). The right lobe is in general control of language, whereas the left (generally) controls nonverbal activities (Wickens, 2005). Damage to or dysfunction in the frontal lobe can result in radically inappropriate emotional responses and an inability to function in an appropriate and socially acceptable manner (Stuss, Gow, & Hetherington, 1992). Residing inside are many of the neurons sensitive to dopamine, which are associated with feelings of reward, long-term and emotional memory, attention, planning, and motivation (Bird, et al., 2004). The frontal lobes also play an important part in retaining some types of longer-term memories, such as raw emotionally-charged ones communicated from the limbic system (Bird et al., 2004) The frontal lobes translate and modify these raw emotional memories into socially acceptable ones that comply with the moral parameters of normal social rules and behavior (Bird et al., 2004).
Behavioral and Functional Changes from the Damaged Frontal Lobe
Damage to the frontal lobes may cause indecisiveness, apathy, and trouble with focusing and initiating actions (Shammi & Stuss, 1999). Because the frontal lobes are responsible for maintaining homeostasis of the emotions, damage may cause impulsive behavior, mood swings, excessive agitation, irritability, volatile explosive behavior, and survivors are highly vulnerable to substance abuse (Stuss et al., 1992). They may be unconcerned with social demands, and display indifference, depression, incontinence, restlessness, euphoria, chaotic thinking and lack of emotional control (Stuss et al., 1992). Their inability to understand some of the basic concepts intrinsic to human communication leave many individuals with these injuries completely unable to relate to others and withdraw from society (Stuss et al., 1992).
Rationale for Predicted Changes or Deficit
A common effect of frontal damage is radical changes in social behavior and personality, especially when both lobes are injured ("Dysfunction by Location: Brain Dysfunction: Merck Manual Home Edition," n.d.). The frontal lobe maintains the control of social behavior and the ability to understand and adhere to social norms (Stuss et al., 1992). After damage is sustained by the frontal lobe, the radical changes and wild fluctuations in personality are caused by the lack of control over these same social issues (Stuss et al., 1992). Appropriate inhibition and disturbances in reflective self-awareness are severely distorted or nonexistent (Stuss et al., 1992). Without the ability to process the rules of common social norms, behavior can range from excessive argumentation, to passivity and vulgarity (Stuss, et al., 1992). In essence, after sustaining damage to the frontal lobe, individuals do not have the capability to determine social appropriateness and response, nor is their capacity to regard the consequences of behavior intact ("Dysfunction by Location: Brain Dysfunction: Merck Manual Home Edition," n.d.).
An interesting feature of frontal lobe damage is the inability to understand or appreciate humor (Shammi & Stuss, 1999). Through studies, it is evident that the frontal lobe is critical in higher cognitive functions such as humor, emotions, and the definitive characteristics of individual personality (Shammi & Stuss, 1999). This brain structure takes raw information, integrates, and translates it according to human definition and social rules (Shammi & Stuss, 1999). A recent focus of research is the ability of humans to attribute mental states to others, referred to as mentalizing, and is vital for the ability and comprehension of human social interaction (Bird, et al., 2004). This mental ability resides in the frontal lobe and gives validity and reason to the social incapacity sustained with injury to this area (Bird, et al., 2004). Embracing the basic social and other functions of this brain part, it is evident that social inclusion and the ability to function within the acceptable parameters of the communal nature of humankind is radically disrupted (Stuss et al., 1992).
Treatments and Future Research
Researchers have discovered some tests that determine the extent of injury to the frontal lobe, and focus on specific areas of cognitive development (Center for Neuro Skills, 2010). The Wisconsin Card Sorting Test focuses on response and inhibition; The Tapping Test on motor skills; and The Toke Test addresses language skills (Center for Neuro Skills, 2010). Treatments include administering the drug Ritalin as a means to stimulate the frontal lobe and increase the ability to regulate and control impulsive and inappropriate behavior (Experimental Treatment for Frontal Lobe Injuries, n.d.). Another treatment which has been explored is the drug Sinemet, which is currently used to treat Parkinson’s disease (Experimental Treatment for Frontal Lobe Injuries, n.d.). Research studies show that within 13 days of the drug's administration, there are signs of improvement in the frontal lobe injury (Experimental Treatment for Frontal Lobe Injuries, n.d.). Also promising is the use of neural progenitor cells, which are capable of dividing and changing into several types of brain cells used to replace damaged cells (Experimental Treatment for Frontal Lobe Injuries, n.d.). These cells have been transplanted into the brains of mice with brain injuries, and within one week lasting improvements occurred in their cognitive abilities (Experimental Treatment for Frontal Lobe Injuries, n.d.).
The frontal lobe is the seat of our intrinsically human ability to comprehend the feelings of others, maintain appropriate social relationships, and appreciate humor as one of the distinct traits of humankind (Shammi & Stuss, 1999). The losses suffered from injury to this brain structure change the fundamental nature of the personality, its capacity toward spontaneity and many of the human qualities that produce individuality (Blumer & Benson, 1975). The frontal lobe allows humans to draw feedback from their environment and respond in a way exclusive to the human social network, without which, the intrinsic collective nature of humankind could not exist (Bird et al., 2004). Our ability to function with the complexities of humor, social reason, and emotion, produces some of the fundamental characteristics inherent in human nature (Stuss et al., 1992). The frontal lobe has evolved by and for the complexities of higher cognitive function, and damage to the area produces a devastating intrusion into the basic human capacity for higher thinking and reason, which disrupts the fundamental parameters of the human equation.
Bird, C. M., Castelli, F., Malik, O., Frith, U., & Husain, M. (2004). The impact of extensive medial frontal lobe damage on ‘Theory of Mind’ and cognition. Brain, 127(4), 914-928. doi: 10.1093/brain/awh108
Blumer, D., & Benson, D., 1975. Personality changes with frontal and temporal lobe lesions. In D. Benson and D. Blumer, eds. Psychiatric Aspects of Neurologic Disease. New York: Grune & Stratton.
Center for Neuro Skills. (2010). Frontal Lobe Function. Traumatic Brain Injury Resource Guide. Retrieved October 15, 2010, from http://www.neuroskills.com/tbi/bfrontal.shtml
Dysfunction by Location: Brain Dysfunction: Merck Manual Home Edition. (n.d.). Merck & Co., Inc. - We believe the most important condition is the human one. Retrieved October 13, 2010, from http://www.merck.com/mmhe/sec06/ch082/ch082b.html
Experimental Treatment for Frontal Lobe Injuries. (n.d.). Traumatic Brain Injuries. Retrieved October 13, 2010, from http://www.tbirecoverycenter.org/frontallobe.htm
Levin, H. S., Amparo, E., Eisenberg, H. M., Williams, D. H., High, W. M., McArdle, C. B., & Wiener, R. L. (1987). Magnetic resonance imaging and computerized tomography in relation to the neurobehavioral sequelae of mild and moderate head injuries [Abstract]. Journal of Neurosurgery, 66(5), 706-713.
Shammi, P., & Stuss, D. T. (1999). Humour appreciation: a role of the right frontal lobe. Brain, 122, 657-666. Retrieved October 13, 2010, from http://api.ning.com/files/
Stuss, D. T., Gow, C. A., & Hetherington, C. R. (1992). "No longer Gage": Frontal lobe dysfunction and emotional changes. Journal of Consulting and Clinical Psychology, 60(3), 349-359. doi: 10.1037//0022-006X.60.3.349
Wickens, A. P. (2005). Foundations of Biopsychology (2nd ed.). New York: Pearson/Prentice Hall.